1. Field of the Invention
The present invention relates to a golf ball. More particularly, the present invention relates to an improvement in the sectional shape of a dimple.
2. Description of the Related Art
A golf ball has a large number of dimples on a surface thereof. The role of the dimples resides in one aspect that such dimples disturb an air stream around the golf ball during the flight, thereby causing a turbulent flow separation (which will be hereinafter referred to as a “dimple effect”). A separating point of air from the golf ball is shifted backward by the turbulent flow separation so that a drag coefficient (Cd) is reduced. By the reduction in the drag coefficient, the flight performance of the golf ball can be enhanced.
An improvement in the sectional shape of the dimple intended for an enhancement in the flight performance has variously been proposed Japanese Laid-Open Patent Publication No. Hei 9-70449 has disclosed a golf ball comprising a double radius dimple having a predetermined shape. Japanese Laid-Open Patent Publication No. 2000-279553 has disclosed a golf ball comprising a dimple in which a peripheral edge portion is a rounded and curved surface.
A golf player is most concerned about the flight distance of a golf ball. In respect of an enhancement in the flight distance, the sectional shape of a dimple has room for an improvement.